Script to FCC authenticate LTE modem

Installing and Using OpenWrt
1

Model BT Home Hub 5A
Architecture xRX200 rev 1.2
Target Platform lantiq/xrx200
Firmware Version OpenWrt 23.05.2 r23630-842932a63d / LuCI openwrt-23.05 branch git-23.306.39416-c86c256
Kernel Version 5.15.137

I have successfully configured a Sierra Wireless EM7455 LTE modem by installing the modules kmod-usb-net-cdc-mbim luci-proto-mbim qmi-util.

The modem is running in MBIM mode and it does not expose an AT command interface. I have read in other posts that it is possible to change the mode of the modem, or expose an AT command interface even while in MBIM mode, but my attempts to do this have all come to nothing.

The reason this matters is that it is necessary to perform FCC authentication on the modem every time it is powered up and at the moment the only way I have found to do this is to run:

qmicli -d /dev/cdc-wdm0 --dms-set-fcc-authentication

If it were possible to get an AT interface to talk to the modem I believe that it might be possible to permanently FCC auth the modem and thus remove the need to run this command. However, failing this what I want to do is to automate the running of qmicli as above by inserting this command somewhere in the process that brings up the MBIM interface /dev/cdc-wdm0.

Please can somebody tell me where I can put this command?

I realise that my description of the problem might be a bit confused because I am way out of my comfort zone here! Apologies if so.

Thanks in advance
John

2

Please see EM7455B connection issues - #8 by AndrewZ

3

Thanks for that Andrew. I've succeeded as far as your "Part 1 disable FCC Auth" but there I'm stuck.
I've downloaded the sierrakeygen.py tool and so am able to do the OPENLOCK and then this:

AT!PCFCCAUTH=1

OK
AT!PCFCCAUTH?

NV Setting: 1
FCC Auth Enabled: 1
FCC Lock State: 0

But if I understand correctly I need to set all 3 settings to 1? Am I correct in thinking that if I can also set FCC Lock State to 1 then FCC Auth Enabled will be permanently set to 1? But exactly how do I do that?

Thanks!
John

4

Standard command to save settings is AT&W

5

no, you need to set it to 0, then reset the modem and re-check with AT!PCFCCAUTH?
The goal is to see all zeros.

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6

And run &w and check if &f or reboot does not destroy saved setting.

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7

This is not necessary, otherwise I would have mentioned it.

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8

Thanks Andrew, now I've got all the zeros as required :slight_smile:

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